fix(remix): Attempt to extract user IP from request headers.

packages/remix/src/utils/getIpAddress.ts

@@ -0,0 +1,79 @@
+// Vendored / modified from @sergiodxa/remix-utils
+// https://github.com/sergiodxa/remix-utils/blob/02af80e12829a53696bfa8f3c2363975cf59f55e/src/server/get-client-ip-address.ts
+
+import { isIP } from 'net';
+
+/**
+ * This is the list of headers, in order of preference, that will be used to
+ * determine the client's IP address.
+ */
+const headerNames = [
+  'X-Client-IP',
+  'X-Forwarded-For',
+  'Fly-Client-IP',
+  'CF-Connecting-IP',
+  'Fastly-Client-Ip',
+  'True-Client-Ip',
+  'X-Real-IP',
+  'X-Cluster-Client-IP',
+  'X-Forwarded',
+  'Forwarded-For',
+  'Forwarded',
+];
+/**
+ * Get the IP address of the client sending a request.
+ *
+ * It receives a Request headers object and use it to get the
+ * IP address from one of the following headers in order.
+ *
+ * - X-Client-IP
+ * - X-Forwarded-For
+ * - Fly-Client-IP
+ * - CF-Connecting-IP
+ * - Fastly-Client-Ip
+ * - True-Client-Ip
+ * - X-Real-IP
+ * - X-Cluster-Client-IP
+ * - X-Forwarded
+ * - Forwarded-For
+ * - Forwarded
+ *
+ * If the IP address is valid, it will be returned. Otherwise, null will be
+ * returned.
+ *
+ * If the header values contains more than one IP address, the first valid one
+ * will be returned.
+ */
+export function getClientIPAddress(headers: Headers): string | null {
+  const ipAddress = headerNames
+    .map((headerName: string) => {
+      const value = headers.get(headerName);
+      if (headerName === 'Forwarded') {
+        return parseForwardedHeader(value);
+      }
+      if (!value?.includes(', ')) return value;
+      return value.split(', ');
+    })
+    .reduce((acc: string[], val) => {
+      if (!val) {
+        return acc;
+      }
+
+      return acc.concat(val);
+    }, [])
+    .find(ip => {
+      if (ip === null) return false;
+      return isIP(ip);
+    });
+
+  return ipAddress ?? null;
+}
+
+function parseForwardedHeader(value: string | null): string | null {
+  if (!value) return null;
+  for (const part of value.split(';')) {
+    if (part.startsWith('for=')) return part.slice(4);
+    continue;
+  }
+  return null;
+}

packages/remix/src/utils/web-fetch.ts

@@ -1,6 +1,7 @@
 // Based on Remix's implementation of Fetch API
 // https://github.com/remix-run/web-std-io/tree/main/packages/fetch
 
+import { getClientIPAddress } from './getIpAddress';
 import { RemixRequest } from './types';
 
 /*
@@ -92,6 +93,15 @@ export const normalizeRemixRequest = (request: RemixRequest): Record<string, any
     headers.set('Connection', 'close');
   }
 
+  let ip;
+
+  // Using a try block here just to stay on the safe side
+  try {
+    ip = getClientIPAddress(headers);
+  } catch (e) {
+    // ignore
+  }
+
   // HTTP-network fetch step 4.2
   // chunked encoding is handled by Node.js
   const search = getSearch(parsedURL);
@@ -116,6 +126,9 @@ export const normalizeRemixRequest = (request: RemixRequest): Record<string, any
 
     // [SENTRY] For compatibility with Sentry SDK RequestData parser, adding `originalUrl` property.
     originalUrl: parsedURL.href,
+
+    // [SENTRY] Adding `ip` property if found inside headers.
+    ip,
   };
 
   return requestOptions;